Device and method for monitoring a tablet press machine, preferably during continuous operation,by means of a measuring device attached to a press punch

ABSTRACT

The invention relates to a punch for a tableting machine. The punch preferably has a measuring device that can function in an energy self-sufficient manner independently of the power supply to the tableting machine. Furthermore, the invention relates to a tableting machine comprising the above-mentioned punch and a method for monitoring a tableting machine with the punch according to the invention during operation.

The invention preferably relates to a punch for a tableting machine. Thepunch preferably has a measuring device that can function independentlyof the power supply to the tableting machine.

Furthermore, the invention preferably relates to a tableting machine anda system which includes the above-mentioned punch.

Additionally, the invention relates to a method for monitoring atableting machine with the punch according to the invention duringoperation. The measuring device of the punch preferably comprises asensor, a computing unit and a communication unit as well as a memoryunit. The sensor of the measuring device records physical or chemicalmeasured values. Subsequently, the communication unit of the measuringdevice preferably sends the recorded measured values of the sensor to aprogrammable logic controller of the tableting machine and/or to a dataprocessing unit and/or the recorded measured values of the sensor arepreferably saved on the memory unit of the measuring device.

PRIOR ART

Tableting machines are primarily used for the production of tablets onan industrial scale. Tableting machines are based on the principle thatin a first step a die is filled with a powder mixture to be tableted.The mixture is then compressed into a tablet by the interaction of anupper punch and a lower punch. Modern tableting machines can produceseveral million tablets per hour with multi-tip tooling.

The large number of compression procedures leads to wear on the toolingand can also generate wear on various components of the tabletingmachine. Furthermore, set machine parameters may prove to be no longeroptimally suited for the compression procedure in the course ofoperation, for example due to temperature changes in the machineenvironment and/or vibrations. Both wear and unsuitable operatingparameters can therefore lead to defective compression procedures anddamage components of the tableting machine as a whole. Various types ofmeasuring equipment are used in the prior art for monitoring suchdefects. An essential component of a measuring device is a sensor.

A sensor (also detector or transducer or probe) is a technical componentand preferably the first element of a measuring chain in a measuringdevice. A sensor can determine physical (e.g. heat quantity,temperature, humidity, pressure, sound field parameters, brightness,acceleration) or chemical (e.g. pH value, ionic strength,electrochemical potential) properties and/or the material composition ofits environment qualitatively or quantitatively as a measured variable.These variables are detected by means of physical or chemical effectsand converted into an electrical signal that can be processed further.Sensors within machine tools, in particular forming machines such aspresses or punches, are well known.

DE 10 2006 002 359 B4 discloses a tableting machine in the form of arotary tableting machine that has a temperature sensor in the immediatevicinity of its die. The sensor is stationary, not rotating with theturret, e.g. attached to the machine frame. In particular, the sensorrecords temperature values of the tablets in production in order tomonitor the production process.

A disadvantage of such a tableting machine is that only one physicalproperty can be recorded, namely the temperature inside the compressionarea. Furthermore, the temperature can only be measured when stationaryat one point in the compression area.

DE 10 2005 051 567 B4 discloses a tableting machine—a rotary tabletingmachine—as well as a method for displacement measurement of a punch.Here, the punches of the rotary tableting machine are equipped withmarkers. The rotational movement of the punches causes them to pass astationary sensor (mounted outside the turret). This sensor records thechanges in position of the markers, which are then evaluated.

The document DE 195 02 596 C2 describes sensors and measuring devicesfor monitoring the tableting process. Here, force sensors are attachedto both an upper and a lower compression roller in order to determinecompression force values of a pair of punches. In conjunction with theturret position, the measurements and previously determined machineparameters are used to measure and calculate displacement-compressionforce assignments.

The disadvantage of this arrangement is that the compression force isnot measured directly at the punches. Between the sensor and the punchthere are components (compression roller, compression roller bearing,compression stations) of different strength and rigidity. Thesecomponents influence the quality of the force measurement. Anotherdisadvantage is the fact that only one physical property can be recordedusing this sensor arrangement, namely the force acting on thecompression roller through the punch.

An essential element for the functionality of tableting machines is thepunch, which is why it is particularly important to monitor it. In theprior art, some forming machines, in particular tableting machines, areknown that comprise a sensor that is adapted to monitor compressionforces on a punch. However, the known designs for monitoring compressionforces on punches have significant disadvantages, as will become clearin the following.

The document DD 294 457 A5 describes a sensor for force measurement ontableting machines. Here, a force sensor is installed in a piston body.A punch is attached to this piston body, so that the force sensor isarranged above the punch (in the case of the upper punch) or below (inthe case of the lower punch). The force sensor is wired to a powersource via a corresponding hole in the piston body.

The disadvantage of force measurement with such an arrangement is thatit cannot be implemented practically in tableting machines which aredesigned as rotary tableting machines. Punches in rotary tabletingmachines are directly guided by control cams. It is not feasible tomount each punch in a piston body and also to ensure the external powersupply of the punches.

In addition, this arrangement of sensors in DD 294 457 A5 is providedexclusively for determining forces during a compression procedure. Thedetection of occurring forces, which can occur in a punch before orafter a compression procedure, are not to be detected by means of thearrangement described in the document. Furthermore, the acceleration ortemperature of the punch is also not possible solely because of theposition of the sensor.

Such an arrangement also has disadvantages for eccentric tabletingmachines. For example, the punch must be mounted in a specificallydesigned piston body, whereby, among other things, no different loadspartially occurring within the punch can be measured. These can beobtained, for example, disadvantageously, if the punch is notperpendicular to the powder material to be compressed.

The document DE 101 35 283 C2 discloses a method for compressing powdermaterial. Deformations of the die table are measured or calculated fordifferent compression forces. The sensors for force measurement are indirect connection with the punches and are mounted above (upper punch)and below (lower punch) the punches. The sensors are mounted on thecontact surface of the punch heads of the punches.

Such a method is also not feasible from a practical point of view fortableting machines that are designed as rotary tableting machines, sincein rotary tableting machines the punches are guided via control cams.The punches come into direct contact with the compression rollers of therotary tableting machine with their punch head, so it is not practicalto mount a sensor on the punch head.

Thus, there is a need for improvement to provide measurement techniquesthat can be easily and reliably integrated into a tableting machine orprocess, allowing continuous measurement and monitoring of processparameters.

OBJECTIVE OF THE INVENTION

The objective of the invention is to eliminate the disadvantages of theprior art and to provide an apparatus as well as a method for tabletingmachines to determine physical and/or chemical properties directly aswell as continuously on and/or in a punch. In particular, it was anobjective of the invention to provide means for the integration ofmeasuring devices into a tableting machine, which are characterized by ahigh degree of flexibility and accuracy, in order to enable continuousmeasurements and/or monitoring of a variety of process parameters withrespect to a punch in a tableting process.

SUMMARY OF THE INVENTION

The objective according to the invention is solved by the features ofthe independent claims. Advantageous embodiments of the invention aredescribed in the dependent claims.

In a preferred embodiment, the invention relates to a punch for atableting machine, characterized in that the punch has a measuringdevice which can function independently of a power supply to thetableting machine.

Since the punch of the tableting machine has a measuring device,measured variables that are directly related to this punch can berecorded without having to factor out the influences of othercomponents. In addition, the mounting is possible in a simple mannerwithout connection to the power supply of the tableting machine.Furthermore, due to the rotating punch in the case of a rotary tabletingmachine, the measuring device is advantageously not fixed in astationary position at one location in the tableting machine. As aresult, physical or chemical properties (e.g., measurement oftemperature) can be recorded continuously throughout the rotation of theturret of a rotary tableting machine. Accordingly, the present inventionadvantageously enables the recording of measured values before, duringand after a compression procedure, in contrast to known prior artdevices.

In terms of the invention, the tableting machine is preferably a rotarytableting machine or an eccentric tableting machine.

According to the invention, the punch is preferably designed in such away that it has a punch head, a punch barrel and a punch tip. The personskilled in the art is familiar with the terms punch head, punch barreland punch tip. The measuring device is preferably comprised in the punchshaft or incorporated therein.

In a further preferred embodiment, the punch is characterized in thatthe measuring device has a sensor for recording physical and/or chemicalproperties of the punch and/or its environment. Physical properties aredefined, for example, by heat quantity, temperature, humidity, pressure,sound field parameters, brightness, acceleration. Chemical propertiesare, for example, pH value, ionic strength, electrochemical potential.The properties can be recorded qualitatively or quantitatively as ameasured variable.

Particularly preferably, the measuring device comprises severaldifferent sensors which record different physical or chemical properties(of the punch and/or its environment) in parallel at the same time. Thecombination of a plurality of different recorded measured valuesadvantageously improves the accuracy of a statement about the conditionof components of the tableting machine or the production process.

In a preferred embodiment of the invention, the punch is characterizedin that the measuring device has a sensor, in particular for recording aforce, a temperature or an acceleration of the punch and/or itsenvironment. By recording these values, a statement can advantageouslybe made about the wear and functionality of the punch and/or thetableting machine in general.

In a further preferred embodiment of the invention, the punch ischaracterized in that the measuring device has a plurality of sensorswhich are adapted to measure the compression force, the temperatures ofthe punch and the punch tip, and to measure the linear and rotationalaccelerations of the punch. By measuring these values, statements canadvantageously be made about the compression procedure, thefunctionality of the punch and the wear in general.

In a preferred embodiment, the measuring device comprises an activesensor. Active sensors generate a voltage due to their measuringprinciple and do not require any electrical auxiliary power. Activesensors can be, for example, thermocouples, light sensors or pressuresensors. The installation of active sensors advantageously entails lowerenergy consumption.

In a further embodiment, the sensor of the measuring device is designedas a passive sensor. Passive sensors contain passive components whoseparameters are changed by the measured variable. These parameters areconverted into electrical signals by primary electronics. This requiresexternally supplied auxiliary power. Passive sensors are, for example:strain gauge load cells, resistance thermometers, strain gauges,magnetic field sensors (Hall probe). Passive sensors have the advantageof providing particularly accurate measurement results.

In a preferred embodiment of the measuring device, the sensor is atemperature sensor. By detecting a temperature, conclusions can be drawnabout the function of the punch guide and the lubrication, which canprovide information about wear. By recording the temperature and thetemperature curve of the punch tip, corresponding conclusions can bedrawn about a compression procedure.

Furthermore, by monitoring the temperature of the punch and/or itsenvironment, it is possible preferably to draw conclusions abouttemperature values of the pressing materials. This is highly relevant ina tableting process for temperature-sensitive pressing materials. Thecompression of temperature-sensitive pressing materials can only beaccomplished in certain temperature ranges. The compression process cantherefore be adjusted by the recorded values and/or also aborted ifthese values exceed or fall below a threshold value.

Furthermore, recorded temperature values of the punch can advantageouslybe used to monitor or check compression or expansion of the punch due totemperature fluctuations.

Preferably, the temperature can be recorded in many ways using differentsensors and measuring devices. Preferred sensors for recordingtemperature are listed below. However, the invention is not limited tosensors in general, their method of operation, or their method ofconstruction.

A preferred temperature sensor comprises an NTC thermistor, i.e. a hotconductor. This has a negative temperature coefficient, so that when thetemperature increases, the resistance drops and a higher current flows.However, PTC thermistors, i.e., cold conductors, which have a positivetemperature coefficient, can also preferably be used, so that when thetemperature increases, the resistance increases and a lower currentflows.

In another preferred embodiment, the temperature sensor is designed as asemiconductor temperature sensor. It generates an electrical variableproportional to the absolute temperature. This electrical variable canpreferably be represented in analog or digital form.

In a further preferred embodiment, the temperature sensor comprises atemperature probe with oscillating quartz as the measuring element. Theresonant frequency of the oscillating quartz changes as a function ofthe temperature and can be measured very precisely. According to theinvention, the temperature probes are preferably distributed on theouter surface of the punch body and particularly preferably inside thepunch body.

In another preferred embodiment, the temperature sensor is implementedas a thermocouple. Thermocouples are a pair of metallic conductors madeof different materials that are connected at one end. They convert atemperature difference into an electrical voltage (Seebeck effect).

Other temperature sensor alternatives according to the invention maycomprise ferromagnetic temperature sensors.

In a preferred embodiment of the measuring device, the sensor is adisplacement sensor or clearance sensor. Advantageously, a displacementsensor is able to precisely determine the position of a punch in thetableting machine, so that positional anomalies can be noticedimmediately. Geometric changes in individual elements of the tabletingmachine can also be identified.

In a compression procedure of a tableting machine, the upper and lowerpunches preferably cover a distance that converges towards each other.By measuring this distance via displacement sensors or clearancesensors, it is preferably possible (in combination with a force sensor)to determine a ratio between compression force and displacement, so thatproperties of the compression material, such as elasticity, plasticityand porosity, can be advantageously derived from this.

The determination of a position, a distance or a displacement can beachieved by means of a plurality of measuring principles and thus aplurality of sensor arrangements. Accordingly, the invention is notlimited to the displacement or clearance sensors listed in thisdocument.

It is preferred that the measuring equipment comprises both direct andindirect measuring principles for determining the position, the distanceor the displacement. Furthermore, the measured values can alsopreferably be obtained via the integration of all conceivable lineardisplacement measuring systems in the punch.

In a further preferred embodiment, measured values can be linkedtogether to improve the accuracy and the statement about a condition.For example, the exact turret position in with the context of rotarytableting machines helps to improve the displacement measurement withthe acceleration sensors.

A potentiometric transmitter is used in a preferred embodiment of thedisplacement sensor. The potentiometric transmitter is an electricalresistance component whose resistance values can be changed mechanically(by rotation or displacement). According to the invention, thepotentiometric transmitter is incorporated into a punch in such a waythat it changes its resistance with each rotation of the entire punch.

A similar principle is followed by strain gauges, which are used in analternative embodiment of the displacement sensor according to theinvention. A strain gauge changes its electrical resistance by changingits length and cross-section. Bridge circuits are preferably used tomeasure resistance. They can be used to determine an absolute resistanceor to determine a relative change in resistance. When measuring withstrain gauges, the relative change in resistance is measured, as alreadymentioned. In this context, the person skilled in the art is familiarwith the design of the bridge circuit in connection with the measurementof resistance changes of strain gauges as quarter bridge, half bridgeand full bridge. A strain gauge can preferably be used for detecting thedisplacement in the longitudinal direction of a punch.

Another preferred displacement sensor comprises a capacitive sensor. Thecapacitive sensor consists of two metallic parts insulated from eachother. Together with the measured object, it forms a capacitor withvariable capacitance. The measuring effect is based on a geometricchange in the distance between the two capacitor surfaces or a lateraldisplacement of these, which leads to a change in the effectivecapacitor area.

Another embodiment of a displacement sensor may, for example, preferablybe an inductive sensor. Inductive sensors basically work with aninductance (open coil), a magnetic field is generated which is changedby an object. This measuring principle makes it possible to measureangles, distances and velocities without contact or wear. Preferably, aplurality of coils are used according to the invention.

In another preferred embodiment, the measuring device comprises a forcesensor. The invention is not limited to the sensors for recording forcesset out below. Any force measurement that can be reasonably integratedinto a punch is conceivable to enable use for compression forcemeasurement. Preferably, force sensors are designed as pressure sensors.

In a preferred embodiment of the measuring device, the sensor comprisesa pressure sensor. It has been shown that a pressure sensor within themeasuring device provides good information about the wear of punches. Inaddition, pressure sensors can be used to determine maximum forces thatmust not be exceeded, for example, in order to avoid overloading.

The invention can preferably aim to determine compression forces andcompression force curves. This can focus, for example, on forces withina punch, which already occur before the punch strikes againstcompression rollers.

Depending on the powder to be compressed and the filling, compressionalready takes place in the lowering rail cam of a rotary tabletingmachine. This is not desirable, but unavoidable. In addition, the upperpunch can be pressed by the lower punch against the upper compressionroller or lifting cam of a rotary tableting machine if the settings areincorrect.

Based on the measurement of a compression force curve during a completerotation of a tableting machine which is designed as a rotary tabletingmachine, effects/forces can be detected that were previously notmeasurable in the prior art. This makes it possible, among other things,to detect wear on punches and cam courses that is otherwise notidentifiable from measurements. However, such measurements can showwhich forces are generated when striking the compression roller and howthe compression force develops with different pressing materials becauseit is possible to measure directly.

Continuous information about possible wear of the punches or cam coursescan ensure significantly improved quality assurance. On the one hand,early replacement may be indicated. On the other hand, operatingparameters can be adjusted to minimize progressive wear.

Another preferred pressure sensor is a piezoresistive pressure sensor.Piezoresistive pressure sensors use metallic strain gauges orpressure-sensitive semiconductor chips. The person skilled in the art isfamiliar with the following piezoresistive sensor technologies: ceramicthick-film sensors, metal thin-film sensors, silicon pressure sensorsand piezoresistive silicon sensors.

Another preferred pressure sensor is a piezoelectric pressure sensor. Ina piezoelectric sensor, an electrical voltage is generated in a crystalby means of pressure through charge separation (piezoelectric effect).Pressure causes ions to shift inside the crystal, creating an electriccharge on the surface proportional to the force. The charge istransformed into a proportional electric voltage by a charge amplifier.Any pressure can be set as the zero point of the charge amplifier byderiving (short-circuiting) the charge, thus making pressure changesdirectly measurable.

In another preferred embodiment, the pressure sensor comprises a Hallelement. This pressure sensor operates according to the Hall effect,whereby the magnetic field around the Hall element is changed whenpressure is applied.

In an alternative preferred embodiment of the invention, the pressuresensor is a capacitive pressure sensor. Capacitive pressure sensorscontain two capacitors diffused into a silicon chip. When pressure isapplied, the distances between a diaphragm and two capacitor platesopposite each other are changed in opposite directions, so that thecapacitances change accordingly. Preferably, the capacitors are part ofan internal amplifier whose output signal depends on the differencebetween the capacitances.

In another preferred embodiment, the sensor comprises an inductivepressure sensor. Inductive pressure sensors work with an iron core thatis connected to a membrane. Pressure changes generate a force on themembrane and move it. This causes the position of an iron core to changein opposite directions in two coils: in one, the inductance increases,in the other it decreases. The difference can advantageously bedetermined electrically very precisely.

In a preferred embodiment of the invention, the sensor of the measuringdevice is designed as an acceleration sensor. In a preferred embodiment,some of the sensors already mentioned may also assume the intended useof an acceleration sensor.

The invention is not limited to the acceleration sensors specified belowand may well include other or different sensors for recording anacceleration.

With a preferred measuring device comprising an acceleration sensor, thedisplacement of a punch can preferably be detected. The use of anacceleration sensor is advantageously suitable for this purpose, sinceit does not have to have a base as a zero point or reference. Instead,the displacement is determined indirectly by integrating the measuredacceleration. Nevertheless, it is possible to determine sufficientlyprecise information about the positional displacement of the punch,which can be used both for quality assurance of the compressed productsand for process optimization.

Furthermore, the linking of these measured values with one or morefurther measured values, which are preferably recorded by othermeasuring devices and/or sensors, is preferred. This leads to improvedaccuracy and informative value. In the case of rotary tabletingmachines, for example, the exact turret position can help to improve thedisplacement measurement with the acceleration sensors.

Furthermore, an acceleration sensor can be used in conjunction with theforce measurement to provide information about wear.

In a further preferred embodiment, a measuring device comprising anacceleration sensor is used to measure an impact of a punch. Inaddition, the punch can preferably be used to determine aforce-displacement diagram. In particular, a displacement can becalculated from linear and rotational accelerations.

In the sense of the invention, a piezoelectric acceleration sensor ispreferably used. Here, a piezoceramic sensor plate converts dynamicpressure fluctuations into electrical signals that can be processedaccordingly. The pressure fluctuation is generated by a (seismic) massattached to the piezoceramic and acts on the piezoceramic when theoverall system is accelerated.

The acceleration sensor may also preferably be formed by amicro-electro-mechanical system (MEMS). This sensor is a spring-masssystem in which the “spring” is preferably a silicon bar only a fewmicrometers (μm) wide. In addition, the mass is preferably also made ofsilicon. Due to the deflection during an acceleration of the punch inthe tableting machine (e.g. during start-up of the turret or due to thechange in direction of the up and down movement of the punch), a changein the electrical capacitance can be measured very sensitively betweenthe spring-suspended part and a fixed reference electrode. Theelectronics for evaluating this small change in capacitance ispreferably housed on the same integrated circuit.

In a preferred embodiment of the MEMS, a piezoresistive resistor isattached to a bending beam by ion implantation, which changes itsresistance according to the bending and thus allows conclusions to bedrawn about the acceleration. Ion implantation is known to the personskilled in the art and is preferably used in semiconductor technology tochange the electrical properties of the base material (here: bendingbeam).

In another preferred embodiment, the acceleration sensor comprises astrain gauge. A force on a test mass is determined by determining thedeformation of the fixture (e.g., a rod) using strain gauges. For thepurposes of the invention, the punch may preferably be defined as thetest mass. However, the test mass may also preferably be a massdifferent from the punch, which comprises the measuring device.

In a further preferred embodiment of the acceleration sensor, theacceleration is determined via magnetic induction. When the test masssuspended on a spring moves, an electric voltage is induced by a magnetin a coil. The test mass is preferably a mass different from the punch,which comprises the measuring device.

In a preferred embodiment, the acceleration sensor is a Ferraris sensor.This measures the relative acceleration without a test mass using eddycurrents.

In another particularly preferred embodiment, the measurement deviceincludes strain gauge full bridges, integrated MEMS sensors, andtemperature sensors.

In the sense of the invention, the communication unit in the measuringdevice preferably serves for wireless transmission of recorded data ofthe sensor. Accordingly, the communication unit is preferably atransmitting unit. In a further embodiment, communication unit is inparticular a transmitting unit and/or a receiving unit. The transmissionis preferably performed by directional or non-directionalelectromagnetic waves, whereby the range of the frequency band used canvary from a few hertz (low frequency) to several hundred terahertz(visible light), depending on the application and the technology used.According to the invention, the following data transmission methods arepreferably used: Bluetooth, WLAN, ZigBee, NFC, Wibree or WiMAX in theradio frequency range, and IrDA and optical directional radio (FSO) inthe infrared and optical frequency ranges, respectively. Advantageously,it has been shown that by transmitting via such a transmitting unit,data can be transmitted wirelessly without loss of information duringcompression procedures in tableting machines, while a sufficient datatransmission rate can be obtained. In a further embodiment, thetransmitting unit and/or receiving unit comprises an antenna.

In one embodiment, wired transmission may be provided in addition or asan alternative to wireless data transmission. In one embodiment, themeasuring device comprises analog and digital outputs (USB, RS232,fieldbus) for a transmission of data via signal conductor. The signalconductor preferably transmits the recorded measurement data to aprogrammable logic controller of the tableting machine and/or to a dataprocessing unit on the one hand, and on the other hand, control commandsare preferably transmitted to the outputs of the measuring device viathe signal conductor.

In a preferred embodiment, the punch is characterized in that themeasuring device comprises a sensor, a communication unit, a memoryunit, an energy storage unit and a computing unit, whereby the measuredvalues obtained as raw data can be processed by means of the computingunit. Advantageously, data (high-resolution measurements) can be savedvia the memory unit so that they can be used at a later time.

In the sense of the invention, the memory unit of the measuring deviceserves in particular to save or store data. According to the invention,recorded measurement data of the sensor are preferably saved in thememory unit. The memory unit is preferably an electronic data carrier. Aflash memory is particularly suitable for compact integration of anelectronic data carrier in the measuring device, although other datacarriers may also be preferred.

In a further preferred embodiment, the measuring device comprises acomputing unit. According to the invention, the computing unit of themeasuring device preferably comprises a processor unit. The processorunit thereby preferably comprises in particular a graphics processor(GPU) and/or a central processing unit (CPU). Both processors are knownto the person skilled in the art. Many computational operations of theraw data can thus preferably already be performed decentrally on themeasuring device. For example, the measurement signal can be sampled athigh frequency. Mean values and min/max values can be determined fromthe raw data by means of the computing unit and transmitted via acommunication unit to a data processing unit and/or programmable logiccontroller of the tableting machine. Advantageously, this saves energyand bandwidth.

In a further preferred embodiment, the measuring device is adapted toprocess recorded measured values as raw data by means of a computingunit and then to store them in the memory of the measuring device and/orto transmit them by means of the communication unit, preferably by meansof Bluetooth, to a data processing unit and/or programmable logiccontroller of the tableting machine. The processing of the raw data canbe represented, for example, in a conversion of the measurement datainto a required format or the reduction to particularly relevantstatements (see above mean values, exceedance of defined thresholdvalues for force/acceleration/temperature/distance etc.).

Preferably, the measuring device comprises a cable output at which apreconditioned measuring signal is output as a universal analog ordigital signal (e.g. 0-10 V, serial).

In a preferred embodiment of the invention, various trigger options forthe memory unit and computing unit of the measuring device are availablefor controlling the acquisition of measurement data, e.g. in particularafter certain time intervals or when threshold values(force/acceleration/temperature) are exceeded. This ensures that a datalogger only stores data when certain events, such as in particular ahigh load, occur. In this way, accumulated collectives of stress factorscan already be recorded in a stressed component. The stored measuredvalues can be read out, for example, after completion of the measurementby means of a data processing unit (e.g. PC) and/or a programmable logiccontroller of the tableting machine via a simple USB connection.

In a further preferred embodiment of the invention, the measuringdevice, preferably its computing unit, is adapted to control and/oraccess to data by a data processing unit and/or a programmable logiccontroller of the tableting machine. For this purpose, for example,control parameters for carrying out the measurement can be sent to themeasuring device. The control parameters can, for example, concern thetype of measurement or a selection of active sensors (in the case of aplurality of sensors), a timing of the measurement or also instructionsfor the preparation or pre-evaluation of the raw data.

The data processing unit can be, for example, a tablet computer,smartphone or PC, preferably with a computer program product(application/“app”) installed on it for controlling and/or accessing thedata.

Preferably, the communication unit of the measuring device ensures anexchange of data between the app and the measuring device, whereby theapp preferably transmits control commands to the measuring device, whichcan be processed by the computing unit comprised in the measuringdevice.

In addition to controlling the measuring device, the app is preferablyadapted to to access data from the measuring device (or [processed]measured values are transmitted to the communication unit of a tabletcomputer or smartphone using the communication unit of the measuringdevice) and to visualize and/or store this data.

Further preferably, the measurement device has different transmissionmodes, preferably two or more, which differ in terms of bandwidth andpower consumption.

A first transmission mode is preferably defined by direct communicationbetween the measuring device and an external device (smartphone, tabletPC or programmable logic controller of the tablet machine). In the senseof the invention, this transmission mode is called streaming. Inparticular, the transmission mode is characterized by a high data rate.

In a second transmission mode, the measured values of the measuringdevice are preferably transmitted to a distribution unit. Thedistribution unit is connected to a variety of external devices(smartphone, tablet PC or programmable logic controller of the tabletmachine), whereby these can access the data of the distribution unit.This transmission mode is preferably called broadcasting, whereby a highinternal sampling rate (500 Hz) is used to acquire the measuredvariables and form a live mean value, as well as a min/max value, sothat a high data rate is not necessary. The distribution unit canpreferably also be a data processing unit.

In the following, a concrete embodiment as well as application of apreferred measuring device is described. The invention is not limited tothis embodiment.

A preferred measuring device enables a time-synchronous transmission andstorage of recorded measured values of two sensors with strain gaugemeasuring bridges. In addition, integrated MEMS sensors preferablymeasure a rotational speed and a 3-axis acceleration. An integratedprocessor unit preferably processes the sensor data already on themeasuring device and thus advantageously significantly reduces theamount of data to be transmitted. The measuring device preferablyenables simple and continuous monitoring of processes. The recordedmeasurement data and interpreted conditions are preferably transmittedto a distribution unit via Bluetooth, preferably Bluetooth Low Energy4.2. Preferably, a large number of measuring devices can be connected tothe distribution unit in a time-synchronized manner.

Under ideal conditions, the transmission range is up to 30 meters, andmore than 50 devices can be connected to the distribution unit. At thesame time, all measurement data is displayed and optionally stored inthe application of a tablet computer or smartphone. The application ispreferably used to set a calibration value of the measuring device andto configure the outputs of a gateway. The measuring device is furtherpreferably powered by a Li-ion battery and charged by a USB powersupply. The measuring device also preferably has external dimensions of50 mm×13 mm×9 mm. Furthermore, the measuring device preferably has aflash memory with up to 8 Gb.

In a preferred embodiment, the measuring device has strain gauge sensorsin addition to MEMS sensors so that, in addition to force measurement,it is also possible to record accelerations and rotational speeds aswell as orientation. Modern MEMS sensors comprise an integratedtemperature sensor, which means that the temperature can also bemeasured by the measuring device.

In a preferred embodiment of the invention, the measuring device canfunction in an energy self-sufficient manner. With regard to theinvention, the measuring device can thus be used independently of thepower supply of the tableting machine. It has been found that energyself-sufficient measuring devices can be used particularly easily intableting machines operating according to the rotary principle.Moreover, if one sensor power source fails, only one sensor is affected,so that all sensors are independent of each other.

Preferably, the measuring device comprises a battery and/or anaccumulator as energy storage, which makes the measuring device energyself-sufficient in the sense of the invention. A battery and/oraccumulator preferably supplies sufficient energy for the communicationunit to transmit the data.

In a further embodiment, the battery or accumulator preferably suppliesenergy for the functioning of the measuring device. In particular, thecomputing unit, the communication unit and the sensor are simultaneouslysupplied with sufficient energy. Preferably, the measuring devicecomprises an output for a charging connection, for charging theaccumulator.

In another preferred embodiment, an integrated overcharge and dischargeprotection of the accumulator is included in the measuring device forsafe operation of the measuring device.

In another preferred embodiment, the accumulator is designed as a Li-Ionor Li-Po accumulator. Furthermore, the measuring device can comprise anLED display.

In a further preferred embodiment, the measuring device is energyself-sufficient with respect to the power supply of the tabletingmachine by providing induction current/induction. In a preferredembodiment, there is an electrical conductor in the punch that moves ina magnetic field. The magnetic field can preferably be generated by acoil mounted inside and/or outside the turret. The movement of theconductor induces a current which is used for the operation of themeasuring device

In a preferred embodiment, the measuring device comprises a photovoltaiccell (solar cell), which also reacts well to artificial light in machinehalls. By means of the photoelectric effect, light energy is convertedinto electrical energy and the measuring device can be operated in anenergy self-sufficient manner according to the invention. The generatedelectricity is preferably used directly for the measuring operation.

In another preferred embodiment, the generated electricity is stored inabove-mentioned accumulators.

In a further preferred embodiment, the measuring device of a punch isconnected to at least one second measuring device of a second punch. Ina preferred embodiment, the connection is formed by a signal conductor.In a further preferred embodiment of the invention, the connection iswireless via the communication unit. Preferably, power and/or data canbe transmitted via the connection of the measuring devices. Furtherpreferably, all measuring devices can be connected to a distributionunit.

In a preferred embodiment of the invention, the punch is characterizedin that the measuring device is integrated within the punch body.According to the invention, the punch body is preferably defined by thepunch barrel, punch tip and punch head, whereby the punch body ispreferably designed as a thick-walled hollow body or as a solid body.The advantage of an integrated measuring device is that the outergeometry of the punch is not changed, so that the geometric parametersof a tableting machine do not have to be changed due to the punch.

In a further preferred embodiment, the measuring device is preciselyfitted into a punch designed as a solid body. The punch is machined withseparating manufacturing processes in such a way that the measuringdevice can be inserted into the punch in a subsequent assembly process.Preferably, connecting means can also be used here. The measuring devicecan therefore preferably be inserted in the punch in a material-locking,force-locking and/or form-locking manner.

In a preferred alternative according to the invention, the measuringdevice is attached to the inner wall of the thick-walled hollow body ofa punch. Preferably, access to the measuring device can be provided viaa transverse hole to the longitudinal axis of the punch in order to beable to connect signal lines or feed out antennas.

In an exemplary embodiment, the measuring device is inserted into apunch with a shell diameter of 25.4 mm or into a punch with a shelldiameter of 19 mm.

In preferred embodiments, the computing unit of the measuring device isconnected to one or more data processing units and/or a programmablelogic controller of a tableting machine.

In a preferred embodiment, a data processing unit is provided as acomponent external to the tableting machine, which is designed as astand-alone device—independent of the tableting machine.

In a further preferred embodiment, a data processing unit is present asan internal data processing unit. An internal data processing unit canpreferably be a component of the tableting machine and, for example, beintegrated in the frame of a tableting machine. It is preferably alsodesigned as a programmable logic controller of the tableting machine andis preferably also referred to as a machine controller.

In preferred embodiments, the measuring device may communicate with oneor more of the data processing units (e.g., external: PC, smartphone,tablet, or internal: machine control system).

Direct communication between the measuring device and the machinecontrol system allows the operating parameters of the tableting machineto be quickly adjusted on the basis of the measurement results. Forexample, to avoid wear when predefined force limits are exceeded, themachine control system could adjust the operating parameters based onthe transmitted information.

However, communication of the measuring device with an (external) dataprocessing unit, for example a PC, a tablet computer, smartphone, isparticularly preferred. A data processing unit can thus also be designedas an external component (e.g. tablet computer, smartphone). Preferably,the external component communicates with both the measuring device andthe machine control system.

For example, the (pre-processed) measurement results of the measuringunit can first be transmitted to a data processing unit in the form of aPC, tablet computer, etc., or a computer program installed thereon. Bymeans of the external components, a more extensive evaluation of themeasurement results can be carried out, for example, for monitoringand/or logging the tableting process.

On the basis of the evaluation and verification by the personnel, theoperating parameters can, for example, subsequently be adjusted bysending corresponding control commands to the machine control system.

However, the possibility of acquiring and recording the data of themeasuring device on the data processing system already offers a numberof advantages independent of a possible adjustment of the operatingparameters. In particular, recording measurement data can ensure loggingand thus quality assurance of the production process. If predefinedtolerance limits for the compression forces are exceeded, for example,the corresponding compressed products can be marked for furtherinspection. The recording of the measurement data also permits earlydetection of wear, as explained above. Based on the information, repairor replacement of the respective components can be indicated or themaintenance interval can be adjusted.

The invention further relates to a tableting machine comprising a punchof the type mentioned above.

In a further preferred embodiment, the invention relates to a tabletingmachine comprising a programmable logic controller, the lattercomprising at least a computing unit, a communication unit and a memoryunit, and the measuring device of the punch comprising a communicationunit, characterized in that the communication unit of the programmablelogic controller is compatible with the communication unit of themeasuring device of the punch. According to the invention, thecommunication unit of the programmable logic controller can be designedas a transmitting and/or receiving unit. The advantage of integratingthe punch according to the invention into the tableting machine is, inparticular, the possibility of monitoring the tableting machine duringoperation and/or when idle.

In the sense of the invention, compatibility of the communication unitsmeans that they are able to communicate with each other. In the sense ofthe invention, both communication units use the same data transmissionmethods already mentioned above, so that data can be sent or transmittedmutually.

In a further preferred embodiment, the tableting machine is designed asa rotary tableting machine or eccentric tableting machine. A rotarytableting machine preferably comprises a punch of the type mentionedabove, a turret, a die table, a punch guide for receiving punches, apower supply and an upper and lower compression roller.

An eccentric tableting machine preferably comprises a punch of the typementioned above, a die and a power supply.

In further preferred embodiments, a data processing unit, such as asmartphone or tablet computer, comprises a computing unit, acommunication unit, and a memory unit. According to the invention, thecommunication unit of the data processing unit also serves to receivedata from (and/or to send data to) the communication unit of themeasuring device and/or the programmable logic controller of thetableting machine. The communication unit can receive/send the data bycable, but especially a wireless transmission of the data takes place.

In a preferred embodiment, the communication unit of the data processingunit and/or programmable logic controller of the tablet machinepreferably sends data for controlling the measuring device to thecommunication unit of the measuring device.

For example, the communication unit of the data processing unit and/orthe programmable logic controller of the tableting machine can sendcontrol parameters to the measuring device for carrying out ameasurement. The control parameters may, for example, concern a type ofmeasurement or a selection of active sensors (in the case of multiplesensors). Also a timing of the measurement, a preferred transmissionmode or even instructions for the preparation or pre-evaluation of theraw data can be defined.

In a preferred embodiment, the communication unit of the measuringdevice sends data, preferably processed (prepared) measurement data, tothe communication unit of the (external) data processing unit and/or theprogrammable logic controller of the tableting machine.

The data transmitted by the measuring device is preferably stored on thememory unit of the data processing unit and/or programmable logiccontroller of the tableting machine. In the sense of the invention, thememory unit of the data processing unit and/or programmable logiccontroller of the tableting machine preferably serves to save or storedata. According to the invention, preferably recorded measurement dataof the sensor are saved in the memory unit. This concerns both the dataobtained directly via the measuring device and the analysis results ofthe data processing unit and/or programmable logic controller of thetableting machine itself. Preferably, software programs as well as,among other things, command sequences, mathematical and statisticalmodels are also stored on the memory unit, which can be provided asdescribed for controlling the measuring device and/or for accessing(reading out) the data of the measuring device. The memory unit ispreferably an electronic data carrier.

The computing unit of the data processing unit and/or programmable logiccontroller of the tableting machine preferably comprises a processorunit. The processor unit thereby preferably comprises a graphicsprocessor (GPU) and/or a central processing unit (CPU).

In a further preferred embodiment of the invention, at least onemeasuring device is attached to at least one arbitrary element of thetableting machine. Preferably, an arbitrary element means a punch,turret, die plate, punch guide for receiving punches, power supply, andan upper and lower compression roller of a rotary tableting machine.

In another preferred embodiment, the invention relates to a systemcomprising a data processing unit and a tableting machine of the typedescribed above, wherein the measuring device of the punch comprises acommunication unit and the tableting machine comprises a programmablelogic controller, characterized in that the data processing unit and/orthe programmable logic controller of the tableting machine is adaptedto,

-   -   receive and further process measured values from the measuring        device, preferably processed (prepared) raw data, and/or    -   transmit control commands to the measuring device.

Such a system is advantageously suited for monitoring tabletingprocesses, since the measurement data can be processed (visualizedand/or analyzed) on a device external to the measuring device withincreased storage and computing capacity, whereas the measuring devicecan be kept very compact and need only comprise a few components. Thisentails a situation where the evaluation of the data can preferably takeplace online (directly) without the measuring device having to beremoved or read out manually. In addition, the measuring deviceadvantageously records measured values directly at the punch so thatparticularly precise and detailed statements can be made about thecompression procedure. Furthermore, the measuring device can receivecontrol commands from users (or automatically) via external devices(data processing units or a programmable logic controller of thetableting machine) so that certain parameters (e.g. sampling rates) canbe set from a remote position.

In a further preferred embodiment, the invention relates to a method formonitoring a tableting machine using a punch of the type mentionedabove, wherein the measuring device of the punch comprises a sensor, acomputing unit, a communication unit and a memory unit, and thetableting machine comprises a programmable logic controller with acommunication unit, characterized in that

-   -   the sensor of the measuring device records physical and/or        chemical properties;    -   the measured values recorded as raw data are processed        (prepared) by the computing unit of the measuring device;    -   the processed (prepared) measured values are sent to the        programmable logic controller of the tableting machine and/or        data processing unit via the communication unit of the measuring        device and/or the processed (prepared) measured values are saved        on the memory unit of the measuring device.

The advantage of a method according to the invention is the possibilityof monitoring and analyzing the condition of the tableting machineduring operation and/or when idle.

In a further preferred embodiment, the monitoring of the tabletingmachine is preferably a technical monitoring. On the one hand, suchmonitoring is designed to prevent malfunctions and to enable timelymeasures or repairs. On the other hand, it is an effective possibilityfor technical further development and for prevention of environmentaldamage.

In a preferred embodiment, the method is characterized in that thesensor of the measuring device records, in particular, a force,temperature or acceleration of the punch and/or its environment and/orthe speed of the turret.

In a further preferred embodiment, the recorded measured values aresaved in the memory unit of the data processing unit and/or in thememory unit of the programmable logic controller and/or in the memoryunit of the measuring device.

In another preferred embodiment, the method is characterized in that theprogrammable logic controller of the tableting machine and/or the dataprocessing unit, preferably a tablet computer and/or a smartphone, cantransmit control commands to the measuring device, preferably by meansof a computer program product (application/app) installed on thesedevices.

In another preferred embodiment of the invention, the saved measurementdata is preferably analyzed by algorithms.

In a preferred embodiment of the invention, the memory unit of themeasuring device is detachably affixed so that a user of the machine canmanually connect the data to be evaluated to a the programmable logiccontroller of the tablet machine and/or the data processing unit.

In another preferred embodiment of the invention, the computing unit ofthe data processing unit and/or the programmable logic controllerdirectly accesses the measurement data stored in the memory unit of thedata processing unit and/or in the memory unit of the programmable logiccontroller and executes the algorithms for analyzing the measurementdata that are also stored in the memory unit.

By analyzing the measurement data with the help of algorithms, faults,wear and failures of a punch and/or other components of a tabletingmachine can be detected at an extremely early stage.

In a further preferred embodiment of the invention, the method ischaracterized in that the recorded measured values of the measuringdevice are analyzed via machine learning algorithms.

In a further preferred embodiment, external parameters and/or measuredvalues from a punch are incorporated into the analysis of the method formonitoring a tableting machine. These can be determined by measuringdevices that are independent of the measuring device according to theinvention. For example, in the case of rotary tableting machines,recorded measurement data of the compression roller (e.g., compressionforces), the turret (e.g., rotations), the die table or, in a simplecase, the ambient temperature of the tableting machine can also be savedin a memory unit of the data processing unit of the tableting machineand subsequently analyzed by the following algorithms. A large number ofdifferent recorded data allows a comprehensive analysis with few errors.

In a further preferred embodiment, the method is characterized in thatthe recorded measured values of the measuring device are analyzed incombination with externally recorded and/or provided measured values viaalgorithms (preferably machine learning algorithms).

In the sense of the invention, machine learning algorithms are a subareaof artificial intelligence. Machine Learning uses mathematical andstatistical models to “learn” from data sets. In general, machinelearning algorithms have the advantage that information that is toocomplex for a human observer can be automatically extracted from a largedata set. There are a variety of machine learning algorithms that can bebroadly categorized into three different learning methods: supervisedlearning, unsupervised learning, and reinforcement learning.

In a preferred embodiment, supervised learning is used to analyze orprocess the stored measurement data. In the supervised learning method,a so-called training process is first carried out. Here, training datais provided in the form of input data together with the correspondingtarget data. The purpose of training is generally in machine learningmethods to adjust parameters of a function so that the function issubsequently able to determine the target value with high accuracy fromthe corresponding input value. The adapted function is then used afterthe training process to predict target data for previously unseen inputdata. The function is described by a mathematical and/or statisticalmodel.

In a preferred embodiment, the function is designed by support vectormachines, Bayesian networks and/or decision trees. Particularlypreferably, the function is described by an artificial neural network.In accordance with the invention, the artificial neural networks canhave different architectures.

In the sense of the invention, the input data are preferably defined bymachine parameters, environmental parameters and/or measured data of themeasuring device. Machine parameters are preferably rotational speed ofthe turret, various material properties and/or key figures of thecomponents, running time or operating time, age of the machine, numberof punches or other components, etc. Environmental parameters arepreferably ambient temperature, humidity, etc.

Preferably, the measured data from different measuring devices, equippedwith different sensors for measuring different physical and/or chemicalproperties, are used as input data.

According to the invention, target data are preferably adapted to show aprobability for the occurrence of damage, the failure of a component orfor a faulty execution of a pressing process.

In another preferred embodiment, the Unsupervised Learning method isused to analyze or process the stored measurement data. In UnsupervisedLearning, the algorithm attempts to detect patterns in the input datathat deviate from unstructured background noise. The function in thetraining process is oriented only on the similarities of the input dataand adjusts its parameters accordingly, such that no output data is usedfor the training process.

In a preferred embodiment, the Unsupervised Learning method is used tosegment or cluster the input data or, preferably, to compress the inputdata.

In a preferred embodiment, the Unsupervised Learning Algorithmpreferably comprises Principal Component Analysis (PCA) and/or theK-Means algorithm and/or at least one neural network.

As already described, in both methods mentioned above, so-calledtraining processes are carried out in a first step to determine optimalparameters of an above-mentioned machine learning function. Based on theadapted function, various statements are made after the training forpreviously unknown input data.

In another preferred embodiment, the reinforcement learning method isused for the analysis or processing of the stored measurement data. Inthe reinforcement learning method, on the other hand, the trainingprocess takes place continuously even after the parameters of a functionhave been adjusted. Via “trial and error”, effects of differentstatements are observed and evaluated using the adapted function forpreviously unknown input data. In response to these statements, thealgorithm receives feedback, represented abstractly in the form of areward or punishment. Whereupon the algorithm further optimizes thefunction based on its parameters. Accordingly, the algorithmcontinuously adjusts or modifies the function of the machine learningprocess. Preferably, reinforcement learning can use the Q-learningmethod and/or the above-mentioned neural networks and/or further neuralnetworks as well as further algorithms known to the person skilled inthe art.

What is claimed is:
 1. A punch for a tableting machine comprising: ameasuring device that is energy self-sufficient and can functionindependently of a power supply to the tableting machine, wherein themeasuring device comprises a sensor for recording physical and/orchemical properties.
 2. The punch of claim 1, wherein the measuringdevice is incorporated inside a punch body.
 3. The punch of claim 1,wherein the measuring device comprises: a sensor; a communication unit;a memory unit; an energy storage unit; and a computing unit, whereinmeasured values, obtained as raw data, can be processed by means of thecomputing unit.
 4. (canceled)
 5. The punch of claim 1, wherein themeasuring device comprises a sensor for recording a force, atemperature, or an acceleration of the punch or an environment of thepunch.
 6. The punch of claim 1, wherein the tableting machine is arotary tableting machine or eccentric tableting machine.
 7. A tabletingmachine comprising a punch according to claim
 1. 8. A system comprising:a tableting machine comprising a punch according to claim 1; a dataprocessing unit; and a measuring device comprising a communication unit,wherein the tableting machine comprises a programmable logic controller,and wherein the data processing unit or the programmable logiccontroller are adapted to: (i) receive and further process measuredvalues from the measuring device or (ii) transmit control commands tothe measuring device.
 9. A method of monitoring a tableting machineusing a punch according to claim 1, wherein: the measuring device of thepunch comprises a sensor, a communication unit, a computing unit and amemory unit, and; the tableting machine comprises a programmable logiccontroller with a communication unit, wherein: the sensor of themeasuring device records physical or chemical properties; measuredvalues recorded as raw data are processed by the computing unit of themeasuring device; and the processed measured values are sent to theprogrammable logic controller of the tableting machine or dataprocessing unit via the communication unit of the measuring device orthe processed measured values are saved on the memory unit of themeasuring device.
 10. The method of claim 9, wherein the sensor of themeasuring device records a force, temperature or acceleration of thepunch or its environment.
 11. The method of claim 9, wherein theprogrammable logic controller of the tableting machine or the dataprocessing unit can transmit control commands to the measuring device.12. The method of claim 9, wherein the recorded measured values of themeasuring device are analyzed.